Influence of humic substances on the photolysis of aqueous pesticide residues

Garbin, José Roberto; Milori, Débora Marcondes Bastos Pereira; Simões, Marcelo Luiz; Silva, Wilson T. L. da; Neto, L. Martin

doi:10.1016/j.chemosphere.2006.07.017

Cited by 118 publications

(71 citation statements)

References 23 publications

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“…Humic substances and clay particles are known to produce active oxygen species such as hydroxyl radical. 2,21) In the case of the photodegradation of esfenvalerate, the presence of humic acids and clay minerals has been reported to cause either hydroxylation at the 4Ј-position of the 3-phenoxybenzyl moiety or cleavage of the ether bond connecting two phenyl rings; 22,23) therefore, a similar mechanism is likely to occur in the illuminated water-sediment, leading to the formation of IV and V. III would be quickly formed from II, since the photo-induced oxidation of alcohol to the corresponding acid is a well-known pathway. 2) Irrespective of the photolytic mechanism involved, these degradates can be formed much earlier by photolysis than microbial metabolism, which is in accordance with the formation profile of IV.…”

Section: Discussionmentioning

confidence: 99%

Effect of illumination on degradation of pyriproxyfen in water-sediment system

et al. 2011

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Section: Discussionmentioning

confidence: 99%

Effect of illumination on degradation of pyriproxyfen in water-sediment system

et al. 2011

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“…For example, Arnold et al (1998) found that triorganotin cation can form the complexes with negatively charged ligands (i.e., carboxylate and phenolate groups) of the humic acids over the pH range 5.7-9.3. Second, humic acid and its UV degradation products (Garbin et al, 2007) can bind with free radicals and thus function as a powerful free radical scavenger. However, it is not clear why the degradation rate orders are different from each other for MMT, DMT and TMT.…”

Section: Effect Of Humic Acid On Degradationmentioning

confidence: 99%

Ultraviolet degradation of methyltins: Elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

Zhai

Liu

et al. 2008

Chemosphere

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The photodegradation of methyltins, as environmental pollutants, has scarcely been studied so far because of the shortage of rapid and sensitive speciation methods, even though they have very simple structures. The photodegradation of monomethyltin trichloride (MMT), dimethyltin dichloride (DMT) and trimethyltin chloride (TMT) was studied with our new developed HPLC-FPD hyphenated system, which enables rapid and sensitive detection of methyltins. The half-life times and kinetic rate constants of their degradation at different pH were calculated. The results suggest that MMT, DMT and TMT can be degraded under the UV irradiation rapidly at different pH, with a degradation rate sequence of TMT < DMT < MMT. An unknown intermediary product, which is more stable and has higher concentration at pH 8 for MMT and DMT, of methyltin photodegradation was detected for the first time. This unknown intermediary product was identified as methyloltin with electrospray mass spectrometry, and the possible mechanism was proposed based on the intermediary product. The effects of some environmental parameters such as salinity and humic acid on the degradation rate of methyltins were also investigated. Results suggest that salinity and humic acid have strong effect on their degradation, especially for TMT, which was almost never degraded in the solutions containing NaCl and humic acid.

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“…The binding of atrazine to HS has been the subject of many research papers (Neto et al 1994;Garbin et al 2007;Prosen et al 2007;Hutta et al 2011), but the complex interactions are the reason for a controversy discussion on the mechanisms by which these substances are bound: electron transfer, hydrogen bonding, proton transfer resulting in ionic bonds or partitioning into the hydrophobic domains of HS. Other researchers explain the formation of well-known non-extractable chloro-s-triazine residues in soil by chemical binding to HA by heteroatomic bonds after the substitution of a chlorine atom (Neto et al 1994;Yu and Cole 1997;Davies and Jabeen 2003;Zupancic-Kralj, 2005, Prosen et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The interaction between atrazine and the mineral horizon of soil: a spectroscopic study

et al. 2017

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Purpose In this paper, an attempt was made to explain the long-lasting occurrence of atrazine in soil. Despite the fact that this herbicide has been banned in European Union 10 years ago, it is still detected in the environment. Materials and methods Soil samples (organic and mineral horizon), SiO 2 and Al 2 O 3 sorbents were spiked with atrazine. The ultrasound-assisted extraction coupled with gas chromatography-electron capture detector was performed to establish the atrazine recovery depending on the type of soil horizon and sorbent. Fourier transform infrared spectroscopy (FTIR) analysis was conducted to determine the type of interactions between atrazine and sorbents. Results and discussion The atrazine recovery was lower for the mineral horizon (15%) compared to the organic horizon (63%). This finding suggests an interaction between atrazine and the mineral components of soil. Therefore, attempts have been made to explain atrazine's interaction with the main mineral components of soil, SiO 2 and Al 2 O 3 , and to investigate the influence of pH on atrazine's behaviour in soil. The atrazine recoveries were 86.5 and 10.7% for Al 2 O 3 and SiO 2 , respectively. The obtained results demonstrated that the protonated atrazine exhibits stronger interactions with the soil mineral layer (recovery below 0.1%) in comparison to molecular form of atrazine (recovery 86%). FTIR results suggested interactions between atrazine and SiO 2 . FTIR analysis revealed that 1,3,5-azidine ring interacts with SiO 2 molecule. Conclusions In acidic soil, atrazine remediation is limited, especially if the soil contains minerals with high SiO 2 contents. This situation may cause the long-lasting persistence of atrazine in soil.

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Influence of humic substances on the photolysis of aqueous pesticide residues

Cited by 118 publications

References 23 publications

Effect of illumination on degradation of pyriproxyfen in water-sediment system

Effect of illumination on degradation of pyriproxyfen in water-sediment system

Ultraviolet degradation of methyltins: Elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

The interaction between atrazine and the mineral horizon of soil: a spectroscopic study

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